Associative TypeScript Arrays

I'm attempting to organize reservations based on business ID in order to achieve a specific end result. Here is the desired output:

[ [businessID1] => [Object1,Object2, Object3], [businessID2] => [Object1,Object2], [businessID3] => [Object1,Object2] ]

Below is the code I am currently using:

let groups = new Array;
this.reservations.map(function (value) {
  groups[value.businessID] = value;
});

However, this approach is not working as expected because it keeps overwriting the array key. As someone new to the TypeScript/JavaScript world, any guidance or suggestions would be greatly appreciated.

javascriptangulartypescriptionic-framework

Answer №1

In cases where the value is not present, the process involves creating an empty array and then adding the value using the push method:

If the value of groups at businessID is undefined, create an empty array:
if (groups[value.businessID] === undefined) {
  groups[value.businessID] = [];
}
Add the value to the array at businessID:
groups[value.businessID].push(value);

A more concise approach would be:

(groups[value.businessID] = groups[value.businessID] || []).push(value);

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